[Sailor Steve]

That's trying to explain things the hard way. Peter Padfield, in his book Guns At Sea, described naval gunnery as being like trying to hit a ping-pong ball rolling across a mantle at twelve feet with a pistol while sitting in a rocking chair being rocked at random by someone else.

But this goes for both sides. The real reality is that a merchant is not likely to hit a target as small as a submarine, but gamers want to use that to ignore the fact that once the merchant showed that he had the gun to shoot with a submarine captain was not going to risk the lives of his crew by telling himself "They can't hit me from this range, so I'll just stay here and shoot it out with them!"

No, they shouldn't see you on a dark night from any reasonable range. You should be able to sneak up and use torpedoes. But it's just like with the planes - the idea is to make you behave historically and use the submarine like a submarine.